Conventional toilets typically employ a tank mounted above a waste-containing bowl from which a quantity of water is rapidly drained to flush the waste therefrom and into a sewage system. One common toilet design utilizes a flapper valve made of an elastomeric material that normally covers the drain outlet of the tank. When the flush handle on the outside of the tank is depressed by the user, the flapper valve is lifted and the water in the tank moves through the toilet drain outlet and into the sewer system. The flapper valve is designed with an inverted air chamber so that it floats as it is lifted away from the drain outlet in the bottom of the tank. This allows a sufficient amount of flush water to flow into the bowl even if the user immediately releases the flush handle. Additionally, when the water level in the tank drops, it is automatically refilled through a fill valve connected to a high-pressure water supply line.
One of the most common types of fill valves is a ballcock fill valve, which provides a vertical water inlet tube or pipe that is connected to a water supply system. The ballcock fill valve also includes a water valve and a float that is coupled thereto by a long horizontal rod. Typically, such conventional floats are ball-shaped and float on the surface of the water within the tank to monitor its level. When the tank is filled, the water valve is closed to block the inflow of water through the inlet tube. Once a flushing operation has been completed, the water level in the tank drops to nearly the bottom, causing a corresponding drop in the float as well. As a result of the movement of the float, the water valve is opened allowing water from the water supply system to enter the tank. After the water within the tank has reached a predetermined level, the float moves upward, causing the water valve to close, stopping the flow of water into the tank.
Unfortunately, ballcock fill valves require substantial space to accommodate the operation of the lever mechanism that couples the ball float to the water valve. In addition, due to the nature of ballcock valves, they often deliver an imprecise water level when the valve is subjected to different water inlet pressures.
To overcome the drawbacks of ballcock fill valves, pilot valves have been developed. Pilot fill valves include a substantially vertical water inlet pipe that is configured for connection to a water supply at one end and for connection to a main valve structure at another end. In addition, a float structure, which is mechanically coupled to the main valve body by means of a substantially vertical rod, responds to and continually follows the vertical movement of the float. A lever is employed to couple the vertical rod to a pilot valve element provided by the main valve body. As such, the pilot valve element actuates a flexible diaphragm disposed upon a water inlet seat to control the flow of water received from the water supply inlet pipe through the main valve body, thereby controlling the on and off states of the valve.
When the water in the tank falls below its normally filled level immediately following a flushing operation, the lever-controlled pilot element is raised, allowing the diaphragm to in turn rise above the water inlet seat of the valve body. This allows water to flow freely through the main valve and into the tank. When the water level has risen sufficiently within the tank, the lever-controlled pilot element is returned to its lowered position, thereby causing the diaphragm to be repositioned on the water inlet seat, thereby shutting off the flow of water into the tank.
Current pilot fill valves are costly and use various methods to shut themselves off at the correct speed once the tank water level is near full. If the valve takes too long to shut off, a typical user may think that the toilet is leaking when in fact the tank is filling slowly as the valve is near the off position. While various methods have been utilized to prevent slow tank filling near the off position, current pilot fill valves tend to make the valve shut off very quickly, causing the inlet water pipes to rattle and make unpleasant noise.
Therefore, there is a need in the art for a pilot fill valve that utilizes a float having an upper cavity to allow water from an outlet port to be routed and collected to increase the weight of the float. In addition, there is a need for a pilot fill valve having a float with an upper cavity, whereby an overflow allows water collected therein to escape, allowing the weight of the float to be reduced quickly so that the buoyancy forces imparted by the rising tank water remain sufficient to lift the float to ensure the valve is fully turned off.